QUESTION: What is the best way to soundproof our basement so that people in the basement can't hear what's going on upstairs and vice versa. We don't have much headroom for a lot of insulation in our basement ceiling.
--Len Nealer, e-mail
QUESTION: I own a side-by-side home. It was built in 1972. The common wall is the length of the whole house. My problem is that sounds carry right through the common wall. When they play their television or sound system, we cannot hear anything in our home but their noise. Other noises, such as cupboard doors closing, voices, walking etc. are heard all too well in our home. I am sure they hear our noise as well. They are renters on the other side, so there is always someone new living there. Is there anything that can be done to cut the sound, at least a bit, from our neighbours?
--Ellen Horn, e-mail
ANSWER: Both of today's questions relate to a problem that can become quite troublesome for many homeowners at this time of year as we experience a bit of cabin fever. Noise prevention and privacy are becoming an increased concern as we spend more time in our homes in front of the computer, or operating home-based businesses. Many homes are being transformed into workplaces and study halls in addition to places for shelter and family.
Soundproofing one living space from another may often be a difficult task or one that is costly. One main principle to keep in mind is that sound will travel through open air or solid objects, and providing a means of impeding that movement will make things quieter. This is a similar method to that used for insulating homes for heat retention. Insulation traps air, and the heat and moisture contained within it, and prevents it from passing through the insulation easily. It is this same approach that is normally taken when retrofitting homes to minimize sound transfer.
In most cases, insulation used for heat retention will be very effective in reducing noise transfer from one area to another. Fibreglass batts, rigid foam, blown-in foam and other insulation may be used to minimize noise transfer. In Mr. Nealer's situation, the most cost- effective method may be to fill the space between the floor joists with friction fit fibreglass batts. Most homes will have a minimum of seven to nine inches of room below the floor sheathing, which can be easily filled with insulation. The insulation will have to be covered to prevent it from sagging and from shedding fibres to the room below. This is often done with acoustical ceiling tiles or drywall, which also help absorb or reflect sound to varying degrees. If enough headroom exists, a suspended T-bar ceiling with acoustical or insulated tiles is the optimum covering. This style of ceiling allows the tiles to be removed individually, if access to the floor joist space is needed at a later date. A common error often committed by homeowners in this situation is to staple polyethylene sheathing on the underside of the floor joists, below the insulation, to hold it in place or keep it from shedding. This may trap moisture in between the floor joists created from condensation between warm air above the floor and the cooler basement below.
In Ms. Horn's situation adding a soundproofing barrier may be more difficult. The common wall between two halves of a side-by-side are often constructed of concrete block, which has little resistance to sound movement. It may also be built with wooden studs and covered with fireguard drywall on both sides, with nothing in between. Both of these construction methods do little to prevent noise transfer, and is the likely cause of the problems observed.
Adding insulation to one or both sides of the common wall will help prevent noise transfer. Fiberglass batts would not be practical in this case, as an inner wall would have to be built to hold it in place. Rigid foam insulation on the surface of the wall would be an easier alternative. This could be covered with drywall and finished to match the rest of the walls in the home. This could also be covered with panelling or an acoustical sheathing, which would further minimize the sound transfer between dwellings. If the wall is indeed hollow, blown-in foam may be another alternative that will be less disruptive as it can be added without removing or replacing wall coverings. This can be added from one side with minimal patching to do afterward.
Other spray-on coatings, wall coverings and cheaper alternatives may be possible, but may not be nearly as effective as increasing the insulation level between the two living areas in question.
Ari Marantz is owner/inspector of Trained Eye Home Inspection Ltd. and is the PR rep for the Canadian Association of Home Inspectors- Manitoba (www.cahi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358.